New restrictions are in place for boaters near Hawaii's Kilauea volcano after a lava explosion injured 23 people on a sightseeing tour. One woman suffered a broken leg and others were burned when the blast sent rocks crashing through the boat's roof.

"The explosion looked like a gigantic firework, right off the side of the boat," said passenger Kirk Olsen, who says the sightseeing boat was about 100 yards off the coast when a basketball-sized lava bomb crashed through the roof.

"It was suddenly bedlam. There was screaming… You'd look on the floor and there were hot lava rocks glowing," Olsen said.

Th boat that was hit is run by Lava Ocean Tours, one of several companies that takes visitors to see Kilauea's lava pouring into the ocean. Tourists on nearby boats could see the thick plume of steam and hot ash blasting into the sky, reports CBS News' Carter Evans.

Nearly two dozen people on board were treated for burns and scrapes and one woman was hospitalized with a broken femur.

The Coast Guard recently changed the rules for lava tour operators to allow them to take visitors as close as 50 meters from shore. But after Monday's incident boats are required to stay 300 meters out at all times. Kilauea's latest eruption started in early May and the lava flow has now destroyed more than 700 homes.

"What happened today shows the unpredictable nature of a volcano, you just can't know what's going to happen," Olsen said.

Even though the vast majority of the Big Island is unaffected by the lava, concerns about the volcano have hurt tourism there. It's unclear if this accident and the new restrictions will have any further impact.

To see video of the explosion taken from the tour boat, watch the video in the above player